The present invention relates generally to imaging systems with accumulators. Specifically, the present invention relates to improving registration of sheets gathered in accumulators of imaging systems.
Imaging systems such as printers, fax machines, scanners, and copiers are virtually omnipresent, and can be found in homes and offices worldwide. The development of such systems has facilitated improvements in communication that have in turn fostered a sea change in the way people live and work. Telecommuting, paperless offices, and intra-office networks represent but a few examples of the advancements that have been made possible by modern imaging systems.
Since these systems have become crucial to everyday existence, their reliability and smooth operation is paramount. It is therefore vitally important to design imaging systems so that downtime and work interruptions are minimized. This can be a daunting challenge, given the relative complexity of systems in which sheet material must be infed, moved through the imaging process, and outfed in a matter of seconds, or fractions of a second. The challenge is further complicated by the fact that humans are operating the system, thus introducing the factor of operator error as a source of problems.
During operation of such imaging systems, it is typical for a plurality of sheets to be gathered together at a processing station commonly called an xe2x80x9caccumulatorxe2x80x9d. As the sheets are fed individually into the accumulator, slight differences in sheet sizes, weight, thickness, and/or surface textures can cause misalignment, or improper registration, between sheets in the accumulated stack. For each combination of these factors, successful transportation and registration of sheet material depends upon applying the proper amount of applied force on the sheet with a feed mechanism such as a roller.
It is not unusual for sheets handled by feed mechanisms to be at least somewhat out of registration. Consequently, the art reflects mechanisms known as xe2x80x9cjoggersxe2x80x9d to improve registration in the accumulator itself. A typical jogger arrangement is discussed in U.S. Pat. No. 5,072,920 to Kubota et al. This patent is directed to a finisher for an image forming apparatus for stapling or otherwise finishing paper sheets which are sequentially driven out of an image forming apparatus such as a copier or a printer. The finisher is capable of stapling a stack of paper sheets at any desired position or positions of the sack. A pair of reference fences and a pair of jogger fences are provided on a paper receiver for positioning paper sheets in an intended direction of paper transport and a direction perpendicular thereto, respectively. The reference fences and the jogger fences are reciprocatingly movable in a predetermined direction independently of each other, and each is movable in a symmetrical relation. The jogger fences move independently of a stapler, while the reference fences move along with the stapler by being connected to latter.
While known mechanisms are reasonably effective in improving sheet registration, they are accompanied by several drawbacks. For example, joggers usually require additional motors or transmissions, adding to the cost and complexity of the system. Increased complexity frequently means increased service costs and decreased reliability.
It can thus be seen that the need exists for simple, inexpensive, sheet registration mechanism in imaging systems having accumulators.
These and other objects are achieved by providing, in an imaging system including a roller assembly adapted to guide sheet material in the system into an accumulator, a sheet registration assembly. The registration assembly includes a lateral fence extending along a first edge of the accumulator. The lateral fence is adapted to contact a lateral edge of sheets fed into the accumulator. A longitudinal fence extends along a second edge of the accumulator. The longitudinal fence is adapted to contact a longitudinal edge of sheets fed into the accumulator. A helical registration member is mounted in contact with sheet material entering the accumulator and, is adapted for rotation with the roller assembly. Rotation of the helical registration member with the roller assembly causes the helical registration member to exert a force to urge each sheet of material entering the accumulator toward the lateral fence and the longitudinal fence of the accumulator.
In an embodiment, the roller assembly includes a selectively rotating shaft, and the helical registration member is mounted on the shaft. The helical registration member can include a cylindrical core member, with a helical contact surface extending radially from the cylindrical core member. The helical registration member can be fabricated from an elastomeric material, such as urethane.
The helical contact surface can be provided as a plurality of part-helical contact sections. In an embodiment, the part-helical contact sections comprise a plurality of radially extending fingers aligned in a spiral around the cylindrical core.
A method of improving sheet registration in an imaging system including a roller assembly adapted to feed sheet material in the system into an accumulator is also provided. In a first step, a lateral fence is provided extending along a first edge of the accumulator. A longitudinal fence is provided extending along a second edge of the accumulator, the longitudinal fence being substantially perpendicular to the lateral fence. A helical registration member is mounted for rotation with the roller assembly, in contact with sheet material entering the accumulator. When roller assembly feeds individual sheets of sheet material to the accumulator, the helical registration member rotates with the roller assembly, thereby causing the helical registration member to exert a force to urge each sheet of material entering the accumulator toward the lateral fence and the longitudinal fence of the accumulator.
The features of the invention believed to be patentable are set forth with particularity in the appended claims. The invention itself, however, both as to organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings.